List of common misconceptions

This incomplete list is not intended to be exhaustive.

This list describes fallacious ideas and beliefs that are documented and widespread as well as the actual facts concerning those ideas, where appropriate. Inclusion criteria are as follows: a misconception's main topic must have its own article; the misconception must have reliable source(s) which assert that it is a common misconception (or synonym thereof); the misconception and its reference(s) must be present in the topic article; and the misconception must be modern rather than ancient or obsolete.

History

See also: List of misquotations

Ancient to early modern history

• In ancient Rome, Romans did not build rooms called vomitoria in which to purge themselves after a meal. Vomitoria were the entranceways through which crowds entered and exited a stadium.
• There is no evidence that Vikings wore horns on their helmets.
• There is no evidence that iron maidens were invented in the Middle Ages or even used for torture, despite being shown so in some media. Instead they were pieced together in the 18th century from several artifacts found in museums in order to create spectacular objects intended for (commercial) exhibition.
• Christopher Columbus's efforts to obtain support for his voyages were not hampered by a European belief in a flat Earth. Sailors and navigators of the time knew that the Earth was spherical, but (correctly) disagreed with Columbus's estimate of the distance to India, which was approximately one-sixth of the actual distance. If the Americas did not exist, and had Columbus continued to India, he would have run out of supplies before reaching it at the rate he was traveling. Without the ability to determine longitude at sea, he could not have noticed that his estimate was in error in time to return. This longitude problem remained unsolved until the 18th century, when the lunar distance method emerged in parallel with efforts by inventor John Harrison to create the first marine chronometers. The intellectual class had known that the Earth was spherical since the works of the Greek philosophers Plato and Aristotle. Eratosthenes made a very good estimate of the Earth's diameter in the third century BC. (See also: Myth of the Flat Earth)
  

  

  "The First Thanksgiving at Plymouth" (1914) By Jennie A. Brownscombe

• Contrary to the popular image of the Pilgrim Fathers, the early settlers of the Plymouth Colony in present-day Plymouth, Massachusetts did not dress in black, wear buckles, or wear black steeple hats. According to Plimoth Plantation historian James W. Baker, this image was formed in the 19th century when buckles were a kind of emblem of quaintness. This is also the reason illustrators gave Santa Claus buckles.
• Marie Antoinette did not actually use the phrase "let them eat cake" when she heard that the French peasantry was starving due to a dearth of bread. The phrase was first published in Rousseau's Confessions when Marie was only 10 years old and most scholars believe that Rousseau coined it himself, or that it was said by Maria-Theresa, the wife of Louis XIV. Even Rousseau (or Maria-Theresa) did not use the exact words but actually Qu'ils mangent de la brioche ("Let them eat brioche [a rich type of bread]"). Marie Antoinette was a very unpopular ruler and many people therefore attribute the phrase "let them eat cake" to her, in keeping with her reputation as being hard-hearted and disconnected from her subjects.
• George Washington did not have wooden teeth. According to a study of Washington's four known dentures by a forensic anthropologist from the University of Pittsburgh (in collaboration with the National Museum of Dentistry, itself associated with the Smithsonian Museum), the dentures were made of gold, hippopotamus ivory, lead, and human and animal teeth (including horse and donkey teeth).
• The signing of the Declaration of Independence did not occur on July 4, 1776. The final language of the document was approved by the Second Continental Congress on that date, it was printed and distributed on July 4 and 5, but the actual signing occurred on August 2, 1776.
• The United States Constitution was written on parchment, not hemp paper. It is likely that drafts of the document were written on hemp, since a large portion of paper at the time was made from the material.

Modern history

Napoleon on the Bellerophon, a painting by Charles Lock Eastlake depicting Napoleon I, who was taller than his nickname, The Little Corporal, suggests.

• Napoleon I (Napoleon Bonaparte) (pictured) was not particularly short, and did not have a Napoleon complex. After his death in 1821, the French emperor’s height was recorded as 5 feet 2 inches in French feet. This corresponds to 5 feet 6.5 inches in modern international feet, or 1.686 metres. There are competing explanations for why he was nicknamed le Petit Caporal (The Little Corporal), but few modern scholars believe it referred to his physical stature.
• According to Time magazine, there is a common misconception among Americans that Abraham Lincoln freed the American slaves with the Emancipation Proclamation of January 1863. The Proclamation did not cover the 800,000 slaves in the slave-holding border states of Missouri, Kentucky, West Virginia, Maryland or Delaware, pertaining only to areas within rebelling states that were not under Union control. Since those states did not recognize the power of the federal government, most slaves were not immediately freed as a direct result of the Proclamation. Regions in the South that were under Confederate control when the Proclamation was issued ignored its dictum, so slave ownership persisted until Union troops captured further Southern territory. Immediately affected regions were Tennessee, southern Louisiana, and parts of Virginia. It was only with the adoption of the Thirteenth Amendment in 1865 that slavery was officially abolished in all of the United States. Thirty-six of the United States recognize June 19 as a holiday, Juneteenth, celebrating the anniversary of the day the abolition of slavery was announced in Texas in 1865.
• Italian dictator Benito Mussolini did not “make the trains run on time”. Much of the repair work had been performed before Mussolini and the Fascists came to power in 1922. Accounts from the era also suggest that the Italian railways’ legendary adherence to timetables was more myth than reality. Mussolini's trains were subject to frequent labour disruptions due to his conflict with labour unions.
• During the German Invasion of Poland in 1939, there is no evidence of Polish Cavalry mounting a brave but futile charge against German tanks using lances and sabres. This seems to have its origins in German propaganda efforts following the Charge at Krojanty in which a Polish cavalry brigade surprised German infantry in the open and charged with sabres until driven off by armoured cars. While Polish cavalry still carried the sabre for such opportunities, they were trained to fight as highly mobile, dismounted infantry and issued with light anti-tank weapons.
• During World War II, King Christian X of Denmark did not thwart Nazi attempts to identify Jews by wearing a yellow star himself. Jews in Denmark were never forced to wear the Star of David. The Danes did help most Jews flee the country before the end of the war.
• John F. Kennedy's words "Ich bin ein Berliner" are standard German for "I am a Berliner". An urban legend has it that due to his use of the indefinite article ein, Berliner is translated as jam doughnut, and that the population of Berlin was amused by the supposed mistake. The word Berliner is not commonly used in Berlin to refer to the Berliner Pfannkuchen; they are simply called Pfannkuchen. In other parts of Germany, though, the term "Berliner" actually also is used for the product in question, so there is a grain of truth in the myth.
• According to a poll, nearly 20% of Americans incorrectly label Barack Obama as a Muslim, possibly as a result of either misinformation or disapproval. The White House describes Obama as a "devout Christian" who prays every day.

Legislation and crime

• Entrapment law in the United States does not require police officers to identify themselves as police in the case of a sting or other undercover work. The law is specifically concerned with enticing people to commit crimes they would not have considered in the normal course of events.
• It is frequently rumored that the expression "rule of thumb", which is used to indicate a technique for generating a quick estimate, was originally coined from a law allowing a man to beat his wife with a stick, provided it was not thicker than the width of his thumb. In fact, the origin of this phrase remains uncertain, but the false etymology has been broadly reported in media including The Washington Post (1989), CNN (1993), and Time magazine (1983).

Food and cooking

Roll-style Western sushi. Contrary to a popular myth, sushi can contain any number of raw ingredients, including vegetables and other non-meat products.

• Searing meat does not "seal in" moisture, and in fact may actually cause meat to lose moisture. Generally, the value in searing meat is that it creates a brown crust with a rich flavor via the Maillard reaction.
• Some cooks believe that food items cooked with wine or liquor will be non-alcoholic, because alcohol's low boiling point causes it to evaporate quickly when heated. However, a study found that some of the alcohol remains: 25% after 1 hour of baking or simmering, and 10% after 2 hours.
• Sushi does not mean "raw fish", and not all sushi includes raw fish. The name sushi refers to the vinegared rice used in it. Sushi is made with sumeshi, rice which has been gently folded with rice vinegar, salt, and sugar dressing. The rice is traditionally topped by raw fish, cooked seafood, fish roe, egg, and/or vegetables such as cucumber, daikon radish, and avocado. The related Japanese term sashimi is closer in definition to "raw fish", but still not quite accurate: Sashimi can also refer to any uncooked meat or vegetable, and usually refers more to the dish's presentation than to its ingredients. The dish consisted of sushi rice and other fillings wrapped in seaweed is called makizushi, and includes both "long rolls" and "hand rolls".
• Microwave ovens do not cook food from the inside out. Microwave radiation penetrates food and causes direct heating only a short distance from the surface. This distance is called the skin depth. As an example, lean muscle tissue (meat) has a skin depth of only about 1 centimetre (0.39 in) at microwave oven frequencies.
• Placing metal inside a microwave oven does not damage the oven's electronics. There are, however, other safety-related issues: electrical arcing may occur on pieces of metal not designed for use in a microwave oven, and metal objects may become hot enough to damage food, skin, or the interior of the microwave oven. Metallic objects that are designed for microwave use can be used in a microwave with no danger; examples include the metalized surfaces used in browning sleeves and pizza-cooking platforms.
• Swallowed chewing gum does not take seven years to digest. In fact, chewing gum is mostly indigestible, but passes through the digestive system at the same rate as other matter.

Science

Astronomy

A satellite image of a section of the Great Wall of China, running diagonally from lower left to upper right (not to be confused with the much more prominent river running from upper left to lower right). The region pictured is 12 × 12 km (7.5 × 7.5 miles).

• It is commonly claimed that the Great Wall of China is the only man-made object visible from the Moon. This is false. None of the Apollo astronauts reported seeing any specific man-made object from the Moon, and even earth-orbiting astronauts can barely see it, but city lights are easily visible on the night side of Earth from orbit. The misconception is believed to have been popularized by Richard Halliburton decades before the first moon landing. Shuttle astronaut Jay Apt has been quoted as saying "…the Great Wall is almost invisible from only 180 miles up."
• Black holes, unlike their common image, do not necessarily suck up all the matter in the vicinity. They can act as "cosmic vacuum cleaners", but not as much as some people might think. The collapse of a star into a black hole is an explosive process, which means, according to Mass–energy equivalence, that the resulting black hole would be of lower mass than its parent object, and actually have a weaker gravitational pull. The source of the confusion comes from the fact that a black hole exists in a space much smaller but orders of magnitude more dense than a star, causing its gravitational pull to be much stronger closer to its surface. But, as an example, were the Sun to be replaced by a black hole of the same mass (a physical impossibility), then the orbits of all the planets surrounding it would be unaffected.
• Seasons are not caused by the Earth being closer to the Sun in the summer than in the winter. In fact, the Earth is actually farther from the Sun when it is summer in the Northern Hemisphere. Seasons are the result of the Earth being tilted on its axis by 23.5 degrees. As the Earth orbits the Sun, different parts of the world receive different amounts of direct sunlight. When an area of the Earth's surface is oriented perpendicular to the incoming sunlight, it will receive more radiation than it will when it is oriented at an angle to the incoming sunlight. In July, the Northern Hemisphere is tilted towards the Sun giving longer days and more direct sunlight; in January, it is tilted away. The seasons are reversed in the Southern Hemisphere, which is tilted towards the Sun in January and away from the Sun in July. In tropical areas of the world, there is no noticeable change in the amount of sunlight.
  Further information: Effect of sun angle on climate

Biology

Bombus pratorum over an Echinacea purpurea inflorescence; a widespread myth holds that bumblebees should be incapable of flight.

• The claim that a duck's quack does not echo is false, although the echo may be difficult to hear for humans under some circumstances.
• DNA is not made of protein. DNA is instead a nucleic acid. DNA and protein are closely interrelated, however. DNA is always accompanied by proteins in the chromatin of plants and animals. See protein biosynthesis for DNA's involvement in assembling protein. See DNA replication for enzymatic proteins' involvement in assembling DNA.
• The notion that goldfish have a memory span of just a few seconds is false.
• Lemmings do not engage in mass suicidal dives off cliffs when migrating. They will, however, occasionally unintentionally fall off cliffs when venturing into unknown territory, with no knowledge of the boundaries of the environment. This misconception was popularized by the Disney film White Wilderness, which shot many of the migration scenes (also staged by using multiple shots of different groups of lemmings) on a large, snow-covered turntable in a studio. Photographers later pushed the lemmings off a cliff. The misconception itself is much older, dating back to at least the late nineteenth century.
• Bats are not blind. While most bat species do use echolocation to augment their vision, all bat species have eyes and are capable of sight.
• It is a common myth that an earthworm becomes two worms when cut in half. However, only a limited number of earthworm species are capable of anterior regeneration. When most earthworms are bisected, only the front half of the worm (where the mouth is located) can survive, while the other half dies. Also, species of the planaria family of flatworms actually do become two new planaria when bisected or split down the middle.
• According to urban myth, the daddy longlegs spider (Pholcus phalangioides) is the most venomous spider in the world, but the shape of their mandibles leaves them unable to bite humans, rendering them harmless to our species. In reality, they can indeed pierce human skin, though the tiny amount of venom they carry causes only a mild burning sensation for a few seconds. In addition, there is also confusion regarding the use of the name daddy longlegs, because harvestmen (order Opiliones, which are not spiders) and crane flies (which are insects) are also known as daddy longlegs, and share (also incorrectly) the myth of being venomous.
• Poinsettias are not highly toxic. While it is true that they are mildly irritating to the skin or stomach and may sometimes cause diarrhea and vomiting if eaten, an American Journal of Emergency Medicine study of 22,793 cases reported to the American Association of Poison Control Centers showed no fatalities, and furthermore that a strong majority of poinsettia exposures are accidental, involve children, and usually do not result in any type of medical treatment. Additionally, Poinsettias are not highly toxic to cats. According to the ASPCA, poinsettias may cause light to mid-range gastrointestinal discomfort in felines, with diarrhea and vomiting as the most severe consequences of ingestion.
• The flight mechanism and aerodynamics of the bumblebee (as well as other insects) are actually quite well understood, in spite of the urban legend that calculations show that they should not be able to fly. In the 1930s a German scientist, using flawed techniques, indeed postulated that bumblebees theoretically should not be able to fly, although he later retracted the suggestion. However, the hypothesis became generalized to the false notion that "scientists think that bumblebees should not be able to fly."
• Sharks can actually suffer from cancer. The myth that sharks do not get cancer was spread by the 1992 book Sharks Don't Get Cancer by I. William Lane and used to sell extracts of shark cartilage as cancer prevention treatments. Reports of carcinomas in sharks exist, and current data do not allow any speculation about the incidence of tumors in sharks.
• It is not harmful to baby birds to pick them up and return them to their nests, despite the common belief that doing so will cause the mother to reject them.
• Bulls are not enraged by the color red, used in capes by professional matadors. Cattle are dichromats, so red does not stand out as a bright color. It is not the color of the cape that angers the bull, but rather the movement of the fabric that irritates the bull and incites it to charge.

Evolution

Further information: Introduction to evolution and Objections to evolution

Tyrannosaurus rex. Non-avian dinosaurs died out in the Cretaceous–Tertiary extinction event at the end of the Cretaceous period.

• The word theory in the theory of evolution does not imply mainstream scientific doubt regarding its validity; the concepts of theory and hypothesis have specific meanings in a scientific context. While theory in colloquial usage may denote a hunch or conjecture, a scientific theory is a set of principles that explains observable phenomena in natural terms. Evolution is a theory in the same sense as germ theory, gravitation, or plate tectonics.
  See also: Objections to evolution § Status as a theory

A reconstruction of Aegyptopithecus, a primate—and not a monkey—predating the split between the human and Old World monkey lineages in human evolution.

• Evolution does not claim humans evolved from monkeys, chimpanzees or any other modern-day primates. Instead, humans and monkeys share a common ancestor that lived about 40 million years ago. This common ancestor diverged into separate lineages, one evolving into so-called New World monkeys and the other into Old World monkeys and apes. Humans are part of the Hominidae (great ape) family, which also includes chimpanzees, gorillas, and orangutans. Similarly, the common ancestor of humans and chimpanzees, which lived between 5 and 8 million years ago, evolved into two lineages, one eventually becoming modern humans and the other the two extant chimpanzee species.
• Evolution is not a progression from inferior to superior organisms, and it also does not necessarily result in an increase in complexity. A population can evolve to become simpler, having a smaller genome, but devolution is a misnomer.
• According to the California Academy of Sciences, around 41% of U.S. adults mistakenly believe humans and dinosaurs coexisted. However, the last of the dinosaurs died around 65 million years ago, after the Cretaceous–Tertiary extinction event, whereas the earliest Homo genus (humans) evolved between 2.3 and 2.4 million years ago.
• Evolution does not violate the Second Law of Thermodynamics. A common argument against evolution is that entropy, according to the Second Law of Thermodynamics, increases over time, and thus evolution could not produce increased complexity. However, the law does not refer to complexity and only applies to closed systems, which the Earth is not, as it absorbs and radiates the Sun's energy.
  See also: Entropy and life
• Evolution does not plan to improve organism's fitness to survive. For example, an incorrect way to describe giraffe evolution is to say that giraffe necks grew longer over time because they needed to reach tall trees. Evolution doesn't see a need and respond to it. This mistaken view is known as Lamarckism. A mutation resulting in longer necks would be more likely to benefit an animal in an area with tall trees than an area with short trees, and thus enhance the chance of the animal surviving to pass on its longer-necked genes. Tall trees could not cause the mutation nor would they cause a higher percentage of animals to be born with longer necks.

Chemistry

Glass manufacturing in older eras was a slower process, which often resulted in unevenness and impurities when finished in its solid state. Varying thickness throughout older window panes is the result of these impurities, not due to movement of the glass over time.

• Glass is not a high-viscosity liquid at room temperature: it is an amorphous solid, although it does have some chemical properties normally associated with liquids. Panes of stained glass windows often have thicker glass at the bottom than at the top, and this has been cited as an example of the slow flow of glass over centuries. However, this unevenness is due to the window manufacturing processes used in earlier eras, which produced glass panes that were unevenly thick at the time of their installation. Normally the thick end of glass would be installed at the bottom of the frame, but it is also common to find old windows where the thicker end has been installed to the sides or the top. In fact, the lead frames of the windows are less viscous than the panes, and if glass was indeed a slow moving liquid, the panes would warp at a higher degree.

Human body and health

See also: Misconceptions about HIV and AIDS

The senses

An incorrect map of the tongue showing zones which taste bitter (1), sour (2), salty (3) and sweet (4). In reality, all zones can sense all tastes.

• Different tastes can be detected on all parts of the tongue by taste buds, with slightly increased sensitivities in different locations depending on the person, contrary to the popular belief that specific tastes only correspond to specific mapped sites on the tongue. The original tongue map was based on a mistranslation of a 1901 German thesis by Edwin Boring. In addition, there are not 4 but 5 primary tastes. In addition to bitter, sour, salty, and sweet, humans have taste receptors for umami, which is a savory or meaty taste.
• Humans have more than five senses. Although definitions vary, the actual number ranges from 9 to more than 20. In addition to sight, smell, taste, touch, and hearing, which were the senses identified by Aristotle, humans can sense balance and acceleration (equilibrioception), pain (nociception), body and limb position (proprioception or kinesthetic sense), and relative temperature (thermoception). Other senses sometimes identified are the sense of time, itching, pressure, hunger, thirst, fullness of the stomach, need to urinate, need to defecate, and blood carbon dioxide levels.

Skin and hair

• Shaving does not cause terminal hair to grow back thicker or coarser or darker. This belief is because hair that has never been cut has a tapered end, whereas, after cutting, there is no taper. Thus, it appears thicker, and feels coarser due to the sharper, unworn edges. The fact that shorter hairs are "harder" (less flexible) than longer hairs also contributes to this effect. Hair can also appear darker after it grows back because hair that has never been cut is often lighter due to sun exposure.
• Hair and fingernails do not continue to grow after a person dies. Rather, the skin dries and shrinks away from the bases of hairs and nails, giving the appearance of growth.
• Hair care products cannot as such "repair" split ends and damaged hair. They can, however, prevent damage from occurring in the first place, smooth down the cuticle in a glue-like fashion so that it appears repaired, and generally make hair appear in better condition.

Nutrition, food, and drink

• Eight glasses of water a day are not necessary to maintain health. Consuming things that contain water such as juice, tea, milk, fruits and vegetables also keeps a person hydrated.
• Sugar does not cause hyperactivity in children. Double-blind trials have shown no difference in behavior between children given sugar-full or sugar-free diets, even in studies specifically looking at children with attention-deficit/hyperactivity disorder or those considered sensitive to sugar.
• Alcohol does not make one warmer. The reason that alcoholic drinks create the sensation of warmth is that they cause blood vessels to dilate and stimulate nerve endings near the surface of the skin with an influx of warm blood. This can actually result in making the core body temperature lower, as it allows for easier heat exchange with a cold external environment.
• Alcohol does not kill brain cells. Early temperance writers promoted the idea that drinking causes brain cells to die (as well as the assertion that the alcohol in the blood stream could cause people to catch fire and burn alive). According to Queensland Brain Institute director Professor Perry Bartlett, there is no evidence that drinking alcohol leads directly to the death of brain cells. In fact, alcohol has positive health benefits when used moderately and new brain cells are generated on a daily basis. Alcohol can lead indirectly to the death of brain cells in chronic, heavy alcohol users whose brains have adapted to the effects of alcohol, where abrupt cessation following heavy use can cause excitotoxicity leading to cellular death in multiple areas of the brain.
• A vegetarian or vegan diet can provide enough protein. In fact, typical protein intakes of ovo-lacto vegetarians and of vegans meet and exceed requirements. While lower in protein than non-vegetarian diets, adequate but low protein diets have been shown to be beneficial against cancer. A non-vegetarian diet high in protein such as a typical diet in the United States in fact has been shown to be linked to several diseases including osteoporosis, cancer, impaired kidney function, and heart disease. However, a vegetarian or vegan diet is not a cure-all for all human disease, and a strict vegan diet does require supplementatation of Vitamin B-12 for optimal health.

Human sexuality

• A popular myth regarding human sexuality is that men think about sex every seven seconds. In reality, this has not been measured, and as far as researchers can tell, this statistic greatly exaggerates the frequency of sexual thoughts.
• Another popular myth is that having sex in the days leading up to a sporting event or contest is detrimental to performance. Numerous studies have shown that there is no physiological basis to this myth. Additionally, it has been demonstrated that sex during the 24 hours prior to sports activity can elevate the levels of testosterone in males, which potentially could enhance their performance.

The brain

• Mental abilities are not absolutely separated into the left and right cerebral hemispheres of the brain. Some mental functions such as speech and language (cf. Broca's area, Wernicke's area) tend to activate one hemisphere of the brain more than the other, in some kinds of tasks. If one hemisphere is damaged at a very early age, however, these functions can often be recovered in part or even in full by the other hemisphere (see Neuroplasticity). Other abilities such as motor control, memory, and general reasoning are served equally by the two hemispheres.
  

  

  Golgi-stained neurons in human hippocampal tissue. It is commonly believed that humans will not grow new brain cells, but research has shown that some neurons can reform in humans.

• Until very recently medical experts believed that humans were born with all of the brain cells they would ever have. However, we now know that new neurons can be created in the postnatal brain. Researchers have observed adult neurogenesis in avians, Old World Primates, and humans. Adults of these species retain multipotent (see cell potency) neural stem cells in the subventricular zone of the lateral ventricles and subgranular zone of the dentate gyrus. The newborn neurons generated in these areas migrate to the olfactory bulb and the dentate gyrus, respectively, and are believed to integrate into existing neural circuits. However, the function and physiological significance of adult-born neurons remains unclear. Some studies have suggested that post-natal neurogenesis also occurs in the neocortex, an idea that is disputed.
• Vaccines do not cause autism. Although fraudulent research by Andrew Wakefield claimed a connection, repeated attempts to reproduce the results ended in failure, and the research was ultimately shown to be flawed and fraudulent.
• People do not use only ten percent of their brains. While it is true that a small minority of neurons in the brain are actively firing at any one time, the inactive neurons are important too. This myth has been commonplace in American culture at least as far back as the start of the 20th century, and was attributed to William James, who apparently used the expression metaphorically. Some findings of brain science (such as the high ratio of glial cells to neurons) have been mistakenly read as providing support for the myth.

Disease

• Those suffering from flu or cold congestion do not need to avoid dairy because it does not increase mucus production. Drinking milk and/or consuming other dairy products does not increase mucus production.
• Warts on human skin are caused by viruses that are unique to humans (human papillomavirus). Humans cannot catch warts from toads or other animals; the bumps on a toad are not warts.

Miscellaneous

• Waking sleepwalkers does not harm them. While it is true that a person may be confused or disoriented for a short time after awakening, this does not cause them further harm. In contrast, sleepwalkers may injure themselves if they trip over objects or lose their balance while sleepwalking. Such injuries are common among sleepwalkers.
• In South Korea, it is commonly believed that sleeping in a closed room with an electric fan running can be fatal. According to the Korean government, "In some cases, a fan turned on too long can cause death from suffocation, hypothermia, or fire from overheating." The Korea Consumer Protection Board issued a consumer safety alert recommending that electric fans be set on timers, direction changed and doors left open. Belief in fan death is common even among knowledgeable medical professionals in Korea. According to Yeon Dong-su, dean of Kwandong University's medical school, "If it is completely sealed, then in the current of an electric fan, the temperature can drop low enough to cause a person to die of hypothermia." Although an air conditioner transfers heat from the air and cools it, a fan moves air to increase the evaporation of sweat. Due to energy losses, a fan will slowly heat a room.
• Although it is commonly believed that most body heat is lost through a person's head, heat loss through the head is not more significant than other parts of the body when naked. This may be a generalization of situations in which it is true, such as when the head is the only uncovered part of the body. For example, it has been shown that hats effectively prevent hypothermia in infants.
• Eating less than an hour before swimming does not increase the risk of experiencing muscle cramps or drowning. One study shows a correlation between alcohol consumption and drowning, but there is no evidence cited regarding stomach cramps or the consumption of food.
• Drowning is often thought to be a violent struggle, where the victim waves and calls for help. In truth, drowning is often inconspicuous to onlookers. Raising the arms and vocalising are even usually impossible due to the instinctive drowning response. Waving and yelling (known as "aquatic distress") is a sign of trouble, but not a dependable one: most victims demonstrating the instinctive drowning response do not show prior evidence of distress.

Mathematics

Main article: 0.999...

• Contrary to a widespread perception, the real number 0.999...—where the decimal point is followed by an infinite sequence of nines—is exactly equal to 1. They are two different ways of writing the same real number. A 2009 study by Weller et al. states that "Tall and Schwarzenberger (1978) asked first year university mathematics students whether 0.999... is equal to 1. The majority of the students thought that 0.999... is less than 1." Weller et al. go on to describe their own controlled experiment, performed "during the 2005 fall semester at a major research university in the southern United States. Pre-service elementary and middle school teachers from all five sections of a sophomore-level mathematics content course on number and operation participated in the study." The results are striking: "On the question of whether .999...=1, 72% of the control group and 83% of the experimental group expressed their view that .999... is not equal to 1."
• When a sequence of independent trials of a random process is observed to contain a remarkably long run in which some possible outcome did not occur (for example, when a roulette ball ended up on black 26 times in a row, and not even once on red, as reportedly happened on August 18, 1913 in the Monte Carlo Casino), the underrepresented outcome is often believed then to be more likely for the next trial: it is thought to be "due". This misconception is known as the gambler's fallacy; in reality, by the definition of statistical independence, that outcome is just as likely or unlikely on the next trial as always– a property sometimes informally described by: the system "has no memory".

Physics

• The Coriolis effect does not determine the direction that water rotates in a bathtub drain or a flushing toilet. The Coriolis effect induced by the Earth's rotation becomes significant and noticeable only at large scales, such as in weather systems or oceanic currents. In addition, most toilets in the United States inject water into the bowl at an angle, causing a spin too fast to be significantly affected by the Coriolis effect.
• Gyroscopic forces are not required for a rider to balance a bicycle. Although gyroscopic forces are a factor, the stability of a bicycle is determined primarily by inertia, steering geometry, and the rider's ability to counteract tilting by steering.
• The idea that lightning never strikes the same place twice is one of the oldest and most well-known superstitions about lightning. There is no reason that lightning would not be able to strike the same place twice; if there is a thunderstorm in a given area, then objects and places which are more prominent or conductive (and therefore minimize distance) are more likely to be struck. For instance, lightning strikes the Empire State Building in New York City about 100 times per year.
• A penny dropped from the Empire State Building will not kill a person or crack the sidewalk. Due to terminal velocity the speed of a falling penny cannot exceed 30–50 miles per hour regardless of the distance from which it is dropped, as demonstrated on an episode of Mythbusters.

Psychology

• The notion of catharsis holds that frustration and anger should not be bottled up or else a person risks allowing those feelings to accrue and eventually explode in some harmful way. Instead, it recommends that frustration and anger should be released through harmless expression, such as by screaming or punching a pillow. However, experimental psychology has shown that such expression can increase rather than decrease harmful behavior. In one experiment, people who engaged in catharsis (by hitting a punching bag) were significantly more likely to aggress toward a peer shortly afterward than were people who did not engage in catharsis.
• Photographic or eidetic memory refers to the ability to remember images with extremely high precision – so high as to mimic a camera. However, it is highly unlikely that photographic memory exists, as to date there is no hard scientific evidence that anyone has ever had it. Many people have claimed to have a photographic memory, but those people have been shown to have good memories as a result of mnemonic devices rather than a natural capacity for detailed memory encoding.

Sports

Marcos Torregrosa wearing a black belt with a red bar. In some martial arts, such as Brazillian Jiu Jitsu and Judo, red belts indicate a higher rank than black. In some cases, a solid red belt is reserved for the founder of the art, and in others, higher degrees of black belts are shown by red stripes.

• Abner Doubleday did not invent baseball.
  Further information: Origins of baseball § The Abner Doubleday myth
• The black belt in martial arts does not necessarily indicate expert level or mastery. It was introduced for judo in the 1880s to indicate competency of all of the basic techniques of the sport. Promotion beyond black belt varies among different martial arts. In judo and some other Asian martial arts, holders of higher ranks are awarded belts with alternating red and white panels, and the very highest ranks with solid red belts.

Religion

Book of Genesis

• The forbidden fruit mentioned in the Book of Genesis is commonly assumed to be an apple, and is widely depicted as such in Western art, although the Bible does not identify what type of fruit it is. The original Hebrew texts mention only tree and fruit. Early Latin translations use the word mali, which can be taken to mean both "evil" and "apple". German and French artists commonly depict the fruit as an apple from the 12th century onwards, and John Milton's Areopagitica from 1644 explicitly mentions the fruit as an apple. Jewish scholars suggested that the fruit could have been a grape, a fig, wheat, or etrog. Likewise, the Quran speaks only of a forbidden "tree" and does not identify the fruit.
• Common misconception says that Noah was told in the Book of Genesis to bring two of every animal onto his ark. In the book, at Genesis 7:2, he is actually told to bring "seven pairs of every kind of clean animal […] and one pair of every kind of unclean animal" (The cited text is from the NIV Bible, it uses "seven pairs"; some Bibles, such as the King James Version of Genesis 7:2, use simply "seven". The original Hebrew expression is translated as literally "seven, seven"). The confusion apparently arises from Genesis 6:19 where he is told to bring "two of all living creatures".

Buddhism

• The historical Buddha was not obese. The "chubby Buddha" or "laughing Buddha" is a tenth century Chinese folk hero by the name of Budai. In Chinese Buddhist culture, Budai came to be revered as an incarnation of Maitreya, the Bodhisattva who will become a Buddha to restore Buddhism after the teachings of the historical Buddha, Siddhārtha Gautama, have passed away.
• The Buddha is not a god. In early Buddhism, Siddhārtha Gautama possessed no salvific properties and strongly encouraged "self-reliance, self discipline and individual striving." However, in later developments of Mahāyāna Buddhism, notably in the Pure Land (Jìngtǔ) school of Chinese Buddhism, the Amitābha Buddha was thought to be a savior. Through faith in the Amitābha Buddha, one could be reborn in the western Pure Land. Although in Pure Land Buddhism the Buddha is considered a savior, he is still not considered a god in the common understanding of the term.

Christianity

• The Immaculate Conception is not synonymous with the virgin birth of Jesus, nor is it a supposed belief in the virgin birth of Mary, his mother. Rather, the Immaculate Conception is the Roman Catholic belief that Mary was not subject to original sin from the first moment of her existence, when she was conceived. The concept of the virgin birth, on the other hand, is the belief that Mary miraculously conceived Jesus while remaining a virgin.
• Nowhere in the Bible does it say exactly three magi came to visit the baby Jesus, nor that they were kings, rode on camels, or that their names were Casper, Melchior and Balthazar. Matthew 2 has traditionally been combined with Isaiah 60:1–3.

60:1 Arise, shine, for your light has come,

and the glory of the Lord has risen upon you.

2 For behold, darkness shall cover the earth,

and thick darkness the peoples;

but the Lord will arise upon you,

and his glory will be seen upon you.

3 And nations shall come to your light,

and kings to the brightness of your rising.

Three magi are supposed because three gifts are described, and artistic depictions of the nativity after about the year 900 almost always depict three magi. Additionally, the wise men in the actual biblical narrative did not visit on the day Jesus was born, but they saw Jesus as a child, in a house as many as two years afterwards (Matthew 2:11).

• Contrary to popular belief, there is no evidence that Jesus was born on December 25. The Bible never claims a date of December 25, but may imply a date closer to September. The date may have initially been chosen to correspond with either the day exactly nine months after Christians believe Jesus to have been conceived, the date of the Roman winter solstice, or one of various ancient winter festivals.

Islam

• A fatwā is a non-binding legal opinion issued by an Islamic scholar under Islamic law. The popular misconception that the word means a death sentence probably stems from the fatwā issued by Ayatollah Ruhollah Khomeini of Iran in 1989 regarding the author Salman Rushdie, who he stated had earned a death sentence for blasphemy. This event led to fatwās gaining widespread media attention in the West.
• The word "jihad" does not always mean "holy war"; literally, the word in Arabic means "struggle". While there is such a thing as "jihad bil saif", or jihad "by the sword", many modern Islamic scholars usually say that it implies an effort or struggle of a spiritual kind. Scholar Louay Safi asserts that "misconceptions and misunderstandings regarding the nature of war and peace in Islam are widespread in both the Muslim societies and the West", as much following 9/11 as before.

Technology

Inventions

• George Washington Carver did not invent peanut butter, though he reputedly discovered three hundred uses for peanuts and hundreds more for soybeans, pecans, and sweet potatoes.
• Thomas Crapper did not invent the flush toilet; it was invented by Sir John Harrington in 1596. Crapper, however, did much to increase its popularity and came up with some related inventions, such as the ballcock mechanism used to fill toilet tanks. He was noted for the quality of his products and received several Royal Warrants. He was not the origin of the word crap, but his name may have helped popularize it.
• Thomas Edison did not invent the light bulb. He did, however, develop the first practical light bulb in 1880 (employing a carbonized bamboo filament), shortly prior to Joseph Swan, who invented an even more efficient bulb in 1881 (which used a cellulose filament).
• Henry Ford did not invent either the automobile or the assembly line. He did help to develop the assembly line substantially, sometimes through his own engineering but more often through sponsoring the work of his employees.
• Guglielmo Marconi did not invent radio, but only modernized it for public broadcasting and communication. No single person was responsible for the invention of radio.
• Al Gore never said that he "invented" the Internet; Gore actually said, "During my service in the United States Congress, I took the initiative in creating the Internet." Gore was the original drafter of the High Performance Computing and Communication Act of 1991, which provided significant funding for supercomputing centers, and this in turn led to upgrades of a major part of the already existing, early 1990s Internet backbone, the NSFNet, and development of NCSA Mosaic, the browser that popularized the World Wide Web; see Al Gore and information technology.

Transportation

• Toilet waste is never intentionally dumped overboard from an aircraft. All waste is collected in tanks which are emptied on the ground by special toilet waste vehicles. A vacuum is used to allow the toilet to be flushed with less water and because plumbing cannot rely on gravity alone in an aircraft in motion. The infamous blue ice is caused by accidental leakages from the waste tank. Passenger trains, on the other hand, have historically flushed onto the tracks; however, modern trains usually have retention tanks on board the train.

See also

• Common misunderstandings of genetics
• Conventional wisdom
• Counter-intuitive
• Drug urban legends
• Factoid
• Jan Harold Brunvand
• List of misquotations
• List of topics related to public relations and propaganda

• Misnomer
• MythBusters
• Old wives' tale
• Pseudodoxia Epidemica
• Pseudoscience
• Snopes.com
• The Straight Dope
• Tornado myths
• Urban legend

Further reading

• Diefendorf, David (2007). Amazing… But False!: Hundreds of "Facts" You Thought Were True, But Aren't. Sterling. ISBN 9781402737916.
• Green, Joey (2005). Contrary to Popular Belief: More than 250 False Facts Revealed. Broadway. ISBN 978-0767919920.
• Johnsen, Ferris (1994). The Encyclopedia of Popular Misconceptions: The Ultimate Debunker's Guide to Widely Accepted Fallacies. Carol Publishing Group. ISBN 9780806515564.
• Kruszelnicki, Karl (2006). Great Mythconceptions: The Science Behind the Myths. Andrews McMeel Publishing. ISBN 9780740753640. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
• Lloyd, John (2006). The Book of General Ignorance. Harmony Books. ISBN 9780307394910. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
• Lloyd, John (2010). The Second Book Of General Ignorance. Faber and Faber. ISBN 9780571268655. {{cite book}}: Check |isbn= value: checksum (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
• O'Conner, Patricia T.; Kellerman, Stewart (2009). Origins of the Specious: Myths and Misconceptions of the English Language. New York: Random House. ISBN 9781400066605.
• Tuleja, Tad (1999). Fabulous Fallacies: More Than 300 Popular Beliefs That Are Not True. Galahad Books. ISBN 978-1578660650.
• Varasdi, J. Allen (1996). Myth Information: More Than 590 Popular Misconceptions, Fallacies, and Misbeliefs Explained!. Ballantine Books. ISBN 978-0345410498.